Refrigeration apparatus



Oct. 25 1938. L. B. M. BUCHANAN REFRIGERATION APPARATUS Filed April6,1955

' 2 Sheets-Sheet 2' 'F1a;':o.' 64 WARNER EVRPORFITOR n I fl- 1e y 11 1%v '72 EVHPORRTDR v UNITED STATES PATE Patented Oct. 25, 1938 2,133,948REFRIGERATION APPARATUS NT. OFFICE of Pennsylvania Application April 6,1935, Serial-No. 15,003

20 Claims.

My invention relates to refrigeration apparatus, more particularly torefrigeration apparatus embodying a plurality of evaporators operatingat different temperatures, and it has for an .object to provide improvedapparatus.

A further objectis to provide apparatus of the character set forthhaving a minimum number of parts, particularly moving parts such asvalves.

Another object is to provide such apparatus in which the highertemperature evaporator operates at higher pressure to provide increasedefficiency and capacity, and which apparatus has a minimum number ofmoving parts.

A further object is to prevent condensation of gaseous refrigerant inthe lower temperature evaporator when the higher temperature evaporatoris in operation at the higher pressure.

Another object is to provide apparatus of the above type in which themechanism for selecting the evaporator to be refrigerated may bedisposed in the high side of the system rather than in the low side, sothat it need not be heat insulated to prevent condensation of moisture.

In accordance with my invention, I provide a lower temperatureevaporator and a higher temperature evaporator in free communicationwith each other, so that .the pressure therein is always substantiallythe same. I arrange the evaporators, and the connection between them andthe supply of liquid refrigerant, in such manner that liquid refrigerantflows into the low tempera ture evaporator in preference to the highertemperature evaporator. This may be done, for example, by disposing theconnection to the low temperature evaporator, at the point of division,at a lower level than the connection to the higher temperatureevaporator. When refrigeration isto be effected in the lower temperatureevaporator,

liquid refrigerant is supplied only to said lower temperatureevaporator, the higher temperature evaporator remaining dry so thatevaporation of refrigerant cannot take place therein. The superheatingof the vapor in the latter does not affect the low pressure necessaryfor operation of the lower temperature evaporator. Whenrefrigeration isto be effected in the higher temperature evaporator, the lowertemperature evapor'atoris first substantially filled with liquidrefrigerant by reason of the arrangement giving it preference, andthenthe higher temperature evaporator is supplied with liquid refrigerant toeffect evaporation therein. By filling the lower temperature evaporatorwith liquid refrigerant, condensation of vaporous refrigerant therein,which would otherwise be caused by 5 the higher pressure effected byevaporation in the higher temperature evaporator, is avoided.

In the preferred form of my invention, which is claimed herein andseveral modifications of which are illustrated in the drawings, therefrigerating 5 system is charged with such quantity of refrigerant aswill substantially fill the lower temperature evaporator and supplysufiicient liquid refrigerant to the higher temperature evaporator foroperation thereof. There is also provided 10 means for retaining, in apart of the refrigerating system other than the higher temperatureevaporator, suflicient refrigerant, preferably in liquid form, toprevent the higher temperature evaporator from receiving liquidrefrigerant. In this 15 form, refrigeration is provided selectively inthe lower temperature or the higher temperature evaporator by retainingor releasing refrigerant in said retaining means. The refrigerantvaporized in the lower temperature evaporator may be con- 20 veyed tothe compressor through the higher tem perature evaporator, therebysuperheating the vapor and cooling the evaporator.

The above and other objects are efiected by my invention, as will beapparent from the following description and claims taken in connectionwith the accompanying drawings, forming a part of this application, inwhich:

Fig. 1 is a diagrammatic view of one form'of refrigerating systemembodying my invention, showing the lower temperature evaporator inoperation;

Fig. 2 is a similar partial view showing the higher temperatureevaporator in operation;

Fig. 3 is a diagrammatic view of a second embodiment;

Figs. 4 and 5 are detail views of a modified form of retaining means,said figures showing the retaining means in condition for retainingliquid refrigerant and for releasing liquid refrigerant, respectively;

Figs. 6,7, and 8 are diagrammatic views showing additional embodimentsof the invention;

Fig. 9 is a vertical sectional view of a twotemperature refrigeratorembodying the pre- 'ferred form of refrigerating system, the latterbeing diagrammatically shown in parts;

Fig. 10 is a perspective view of the evaporators of Fig. 9;

Fig. 11 isa plan view of a detail, as seen from the line XI -XI of Fig.10;

Fig. 12 is a detailsectional view of the connection between theevaporators and the refrigerant s pply;

Fig. 13 is a diagrammatic view of another form of refrigerating systemrepresenting a further development of the embodiment of Fig. 9; and

Figs. 14 and show additional forms of control systems fortwo-temperature refrigerators.

Referring to Fig. 1 in detail, I show a refrigerator III having acompartment II which is refrigerated to a relatively low temperature byan evaporator I2, and a compartment I3 refrigerated by an evaporator I4to a temperature which is higher than that maintained in the compartmentII. The temperature in the compartment II may be below freezing, inorder to freeze ice and maintain frozen articles, while the temperaturein the compartment. I3 may be above freezing but sufficiently low forthe preservation of food. The evaporator I2 is refrigerated or operated,that is, refrigerant therein is evaporated, at a lower temperature andat a lower pressure than the evaporator I4, and is referred to herein asthe lower temperature or colder evaporator while the latter is referredto as the higher temperature or warmer evaporator. The evaporators areoperated at difierent times, rather than simultaneously; each evaporatorbeing operated at intervals for sufficient periods of time, preferablyunder thermostatic control,.

to maintain the respective temperature in its compartment.

Each evaporator may be of any desired form,

eitherof the flooded type, or of the type knownv in the art as a dryevaporator, although the latter is not dry in operation but contains amixture of liquid and vaporous refrigerant. In the present embodiment,the evaporator I2 is of the flooded type, having a header. I5 andrefrigerant passages I6 extending downwardly from the lower portion ofthe header. The header is formed with an outlet I1 disposed above thepassages I6, preferably at the top of the header, and communicatingthrough a conduit I8 with the warmer evaporator I4. The latter isillustrated in this embodiment as of the dry type, comprising acrossefinned coil, and it preferably has sufiicient area of coolingsurface to maintain the compartment I3 at the desired temperature withminimum temperature difference, so as to maintain a relatively highhumidity of the air in the compartment.

The outlet end of the evaporator I4 is connected through a conduit I9 tothe inlet 2I of a compressor 22, which is enclosed, together with itsdriving motor in a hermetically-sealed casing 23. The compressor and itsmotor may be of any suitable form known in the art. The outlet of thecompressor is connected through a conduit 24 to a condenser 25. Thelatter may be air-cooled by a motor-driven fan 26. The condenser inturnis connected through a conduit 21 to a chamber 28. A conduit 29,which connects the chamber 28 with a high side float valve 3|, has onebranch 32 connected to the bottom of the chamber 28 and a second branch33, the mouth of which communicates with the chamber 28 adjacent thetop. A valve 34 is provided for shutting off flow through the conduit32. The float valve 3! communicates with the header I5 of the evaporatorI2 through a conduit 35.

It will be noted that the outlet I'I, through which refrigerant issupplied to the evaporator I4, communicates with the header I5 in theupper portion thereof, so that refrigerant admitted to the header I5from the conduit 35,

flows, by gravity, into and fills the passages I6 of the evaporator I2in preference to the evaporator I4. Liquid refrigerant passes throughthe outlet I'I into the evaporator I4 only when the evaporator I2 isfilled to the level of the outlet I! in the header I5. A perforatedbaffle 36 is preferably provided in the header I5, below the conduit 35and the outlet l1 and above the pas sages I6, as shown in Figs. 1 and 2,for a purpose hereinafter described.

The refrigerating system is charged with a quantity of refrigerant suchthat, when the valve 34 is open, there is suflicient liquid refrigerantsupplied to the evaporators, as shown in Fig. 2, to fill the evaporatorI2 to the level of the outlet I1 and to supply sufficient liquidrefrigerant to the evaporator I4 to effect evaporation throughoutsubstantially the full length thereof. The space within the chamber 28below the mouth of the branch conduit 33 is such as to retain, when thevalve 34 is closed, a 'suflicient quantity of liquid refrigerant, asshown in Fig. 1, so that there will not be sufficient liquid 1'."frigerant delivered to the header I5 to supply the evaporator I4 butonly suflicient to provide the evaporator I2 with the quantity needed toeffect operation thereof. In the latter case, the liquid level in theheader I5 is maintained below the top of the header in order to providea vapor space to take care of boiling of the liquid. The quantity ofliquid refrigerant retained in the chamber 28 represents substantiallythe quantity of liquid within the evaporator I4 when it is'in operation,plus the liquid displaced by vapor in the evaporator I2 when it is inoperation.

To efiect refrigeration of the compartment. I3, operation of thecompressor 22 and the fan 26 is started and the valve 34 is opened. Thismay be effected by a thermostatic control, a form of which will behereinafter described. All of the condensed refrigerant now passesthrough the chamber 28 and the float valve 3| to the evaporators, asindicated in Fig. 2. This quantity is now sufficient to fill theevaporator I2 with liquid up to the level of the outlet II, in this casecompletely filling the header I5, and to supply the evaporator I4 with asuflicient quantity for effecting evaporation substantially throughoutsaid evaporator. The liquid refrigerant in the evaporator I4 isvaporized by the heat extracted from the compartment I3 and passesthrough the conduit I9 to the compressor 22, wherein its pressure isincreased. It is then conveyed through the conduit 24 to the condenser25 wherein it is condensed and then discharged to the conduit 21 to berecirculated.

As the temperature of the evaporator I4 is higherthan the temperature ofthe evaporator I2, the pressure in the low side of the system, that is,the portion from the discharge side of the float valve to the inlet ofthe compressor, is higher than when-the evaporator I2 is in operation.-This pressure is not sufficiently low to effect evaporation in theevaporator I2, so that the latter remains inactive. In fact, thepressure is sumciently high so that any vapor entering the evaporator I2would tend to condense, but this is avoided or largely minimized byfllling the evaporator I2 with liquid, which does not give off heat whenits pressure is increased as does a vapor. The purpose of the baffle 36is to guide the refrigerant from the conduit 35 as directly as possibleto the outlet H with mini-' mum intermingling with the liquid in theevaporator I2. The liquid coming from the conduit 35 is at a highertemperature than that in the evaporator I2, since it is not subjected toas low 2,183,948 a temperature as that effected when the evaporator I2is in operation. The portion of the conduits 35 and I8 within thecompartment II and the upper portion of the header I5 maybe covered withheat insulating material. The refrigerating action is discontinued whenthe temperature of the compartment I3 has been reduced to the desiredvalue.

To effect refrigeration of the colder compartment II, the compressor 22and the fan 26 are started and the valve 34 is closed, this operationalso'being preferably effected by a thermostatic control. The condensedrefrigerant'conveyed through the conduit 21 is retained in the chamber28 until it reaches the level of the mouth of the branch conduit 33, asindicated in Fig. 1. As the supply of liquid refrigerant to theevaporators is temporarily cut off, continued operation of thecompressor effects evaporation of the liquid refrigerant in theevaporator I4 and of that in the top of the header I5. Most of thelatter refrigerant is forced into the evaporator I4 and evaporated dueto the boiling or evaporation that is effected in the evaporator I2 asthe pressure is reduced. Evaporation takes place for the time being inboth evaporators, but the amount of liquid in the evaporator I4 isgradually reduced to Zero. Thereafter, evaporation takes place only inthe evaporator I2, and when the liquid level in the chamber 28 reachesthemouth of the branch conduit 33, liquid refrigerant is suppliedtherethrough to the evaporator I2. The retaining of the liquidrefrigerant in the chamber 28 reduces the effective refrigerant chargeto the extent that sufficient liquid refrigerant passes into the headerI5 to just supply the evaporator I2. 7

The refrigerating apparatus now operates in the usual manner of arefrigerating system embodying a flooded evaporator such as shown at I2except that the refrigerant vaporized in the evaporator I2 and withdrawnthrough the outlet Il, passes through the evaporator I4. The

refrigerant vapor is superheated therein, effecting some cooling of thecompartment I3,and then discharged through the conduit I9 to becompressed, condensed, and recirculated.

In Fig. 3, I show a modified form of means for retaining the necessaryquantity of refrigerant to reduce the effective charge and permitevaporation in the colder evaporator I2. This means comprises a chamber37 connected btween the evaporators I2'and I4 by conduits 38 and 39,respectively. The conduit 39 is connected to the chamber 37 at a levelhigh enough so that there -may be retained in the chamber 37 below saidconnection the necessary quantity of refrigerant, such as that retainedin the chamber 28 of Fig. 1, for effecting operation of the evaporatorI2. A plunger 4| is provided in the chamber 31 for displacing liquid andhas a core portion 42 adapted to be actuated by a solenoid 43 forraising the plunger 4|.

To effect refrigeration of the evaporator I4 of Fig. 3, the plunger 4iis released and allowed to displace the liquid in the bottom of thechamber 3'1. The level of the liquid is raised so that it flows throughthe conduit 39 into the evapoevaporator 21, in this case, is connecteddirectly to the float valve 3|. The full charge of refrigerant iseffective so that sufficient liquid refrigerant will be passed throughthe header I5 to supply the I4. To effect operation of the evaporatorI2, the solenoid 43 is energized to raise the plunger 4|. Suflicientliquid refrigerant is now retained in the chamber 37 to starve theevaporator l4, so that only the evaporator I2 receives liquidrefrigerant and evaporation is thus effected therein, as will be clear.

In Figs. 4 and 5, I show another form of re frigerant retaining means.This comprises a chamber 44 pivoted to a supporting member 45 in suchmanner as to be movable between the two positions shown in thesefigures. I This chamber may be interposed in any part of therefrigerating system between the condenser and the evaporator- I4; forthis example it will be assumed that it is connected between thecondenser 25 and the float valve 3I flexible conduits 2'! and 29,respectively. When the chamber 44 is tilted downwardly, as shown in Fig.4, it retains liquid refrigerant to reduce the effective charge, and,when it is raised as shown in Fig. 5, it discharges the liquidrefrigerant to the float valve through the conduit 29' so as tocompartment I3 increases to a value indicating need for refrigeration,the increased pressure in the bulb 46 transmitted to the bellows 48causes the latter to raise the chamber 44 through the toggle link 49.The liquid refrigerant retained in I the chamber is released so as tosupply the evaporator I4 therewith for operation thereof in the I mannerpreviously described. When the temperaturein the compartment I3 isreduced to'the desired value, the bellows 48 contracts to move thechamber 44 downwardly to the position shown in Fig. 4. Refrigerant isretained therein for operation of the colder evaporator I2 as alreadydescribed. Suitable control mechanism for starting and stopping thecompressor and the condenser fan is provided for supplying therefrigeration requirements of both compartments. The thermostaticcontrol of Fig. 4 gives preference to the warm compartment when bothcompartments require refrigeration.

It may be arranged to give preference to the colder compartment byplacing the bulb 46 of Fig. 1 by therein and reversing its direction ofoperation with respect to the chamber 44; that is, upon increase intemperature in the colder compartment, the chamber 44 would be tilteddownwardly as shown in Fig. 4. I

In Fig. 6, I show an embodiment of my invention in which a header 5| forthe colder evaporator I2a also serves as the refrigerant retainingmeans.-

The header 5| is provided with two outlets Ila.

and Ill), disposed at upper and lower levels between which liquidrefrigerant is retained. The outlet I'la is connected to the warmerevaporator I4a through a valve 52 and the outlet Ilb is connectedthereto through a looped conduit 53 which extends to a higher levelbefore connecting with the evaporator Ma. The low temperature evaporatorI2a is shown in the form of a'coil, but it is a flooded evaporator inits operation, both ends being connected to the header 5| below theliquid level therein, though preferably at different levels. Obviously,it may be of any desired form of the flooded type.

When the valve 52 is closed, liquid refrigerant is forced through theoutlet 1b to the evaporator lda until the liquid level is brought downto the outlet no, as shown at 54. This is due to the fact; that thevaporous refrigerant formed on the discharge side of the float valve 3|collects in the upper portion of the header 5|. The system is chargedwith sufficient refrigerant to supply the evaporator Ma under thiscondition, and operation thereof is effected in the same manner asalready described. To effect operation of the low temperature evaporatorI2a, the valve 52 is opened. The vaporous refrigerant in the upper partof the header 5| now passes through the outlet |1a to the evaporator Ma,and liquid refrigerant no longer flows through the conduit 53 but isretained in the header 5| for the reason that there is no longer asufficient pressure difference to the outlet HD to retain the necessaryquantity of I liquid refrigerant therebetween, so that the evaporator ladoes not receive liquid refrigerant. The

outlet |1a may be disposed at the higher liquid level now maintained inthe header 5| and shown at 55, so as to draw off the lubricant at thesurface of the liquid. However, it may be disposed at a higher level ifdesired in which case the lubricant will be removed through the outlet|I|b when the evaporator Ma is in operation, particularly in initiatingoperation thereof after previous operation of the low temperatureevaporator |2a.

In Fig. '1, I show an embodiment of my invention in which the lowtemperature evaporator 56 is of the so-called dry type arranged inseries ahead of the warmer evaporator Ma. Inasmuch as relatively warmrefrigerant passes through the evaporator 56 when the warmer evaporatoris in operation, it is disposed in the upper portion of a brine chamber51, the lower portion of which is adapted to effect the cooling action,such as, freezing of water in the ice trays 58. The retaining meanscomprises a chamber 28a, substantially similar to the chamber 26 of Fig.1, and is connected at the bottom to the float valve 3| through aconduit 32a having a valve 34a and adjacent the top through a conduit33a.

To effect refrigeration in the low temperature evaporator 56, the valve34a is closed so as to retain a quantity of refrigerant in the chamber28a. Only sufficient liquid refrigerant passes on to supply theevaporator 56 so that evaporation at low pressure and temperaturetherein is effected. The evaporator 56 cools the brine in the chamber51, which brine circulates by convection to the lower portion'of thechamber to cool the ice trays 58. The vaporized refrigerant is conveyedthrough the evaporator a. and the operation is otherwise the same asalready'described. When the evaporator Ma is placed in operation byopening the valve 34a, the pressure in the low side of the system isincreased due to the higher temperature .of the evaporator Ha.Consequently, relatively warm refrigerant passes through the evaporator56 and heats the brine in the upper portion of the chamber 51. Inasmuchas the warm brine tends to remain at the top of the duit 32b to theconnection 62.

chamber, this heat is not conducted to the ice trays 58 to any greatextent. The arrangement of the evaporator in the upper portion of thebrine chamber-so as to avoid heating of the ice trays when warmrefrigerant is conveyed therethrough is the invention of Graham. S.McCloy.

In Fig. 8, I show a further embodiment including a low temperatureevaporator 59 of the dry type in series with a warmer evaporator. 6|,also of the'dry type. In this embodiment, provision is made forby-passing the low temperature evaporator when the warmer temperatureevaporator 6| is in operation. The retaining means comprises a chamber28b similar to the chamber 28 of Fig. 1 but disposed between the floatvalve'3l and the evaporators, being connected to the former by theconduit 35. The bottom of the chamber 28b' is connected, through aconduit 32b having a valve 341), to a connection 62 between theevaporators 59 and 6|, which connection is disposed at a level above theevaporator 59. A conduit 63 connects theinlet of the evaporator 59 withthe chamber 28b at the upper portion of said chamber. The chamber 281)is disposed at a level as high as or higher than the connection 62.

The operation of this embodiment is as follows. When the valve 34b inthe conduit 32b is closed, liquid refrigerant is retained in the chamber261) until the liquid level reaches the connection with the conduit 63and then flows through said cond'uit to the colder evaporator 59. Onlysufficient liquid is supplied under this condition to effect evaporationin the colder e'vaporator 59, the vaporized refrigerant being conductedthrough the evaporator 6| as in the previous embodiments.

To effect refrigeration in the warmer evaporator, 6|, the valve 341) isopened so as to permit the liquid in the chamber 28b to pass through thecon- The liquid first completely fills the evaporator 59 and then entersthe evaporator 6| 'to effect evaporation therein.. It will be notedthat, with this arrangement, the colder evaporator 59 is flooded whilethe evaporator 6| is in operation, both the connection 62 and thechamber 28b being disposed at higher levels.

Referring to Figs. 9 to 12, I show the embodiment of my invention whichis at present preferred. In this embodiment, the cabinet 64 has a foodliner 65, the interior of which is divided by a horizontal insulatedpartition 66 into a lower,.

relatively cold or freezing chamber 61 and an upper, warmer chamber 68for preservation of food. This arrangement is described and claimed intheapplication of Milton Kalischer, Serial No.

751,324, filed November 3, 1934. The cabinet is also formed with amachine compartment 69, in this case-shown below the food liner, forcontain ing the refrigerating unit.

The colder compartment 61 is refrigerated by an evaporator 1|,comprising a plurality of tubes 12. These tubes are bent into U-shapeand the ends thereof connected to a header 13. The tubes are secured tothe under surface of the bottom wall portion of the food liner 65. Icetrays 14 may be disposed on the bottom of the food liner to berefrigerated-by the evaporator 1|. This arrangement is described andclaimed in the application of J. H. Ashbaugh, Serial No. 751,309, filedNovember 3, 1934. The warmer compartment 68 is refrigerated by anevaporator 15, comprising a serpentine coil secured to the back surfaceof the rear wall portion of the food liner portion 65.

The evaporators 1| and 15 are connected to each otherand to the sourceof liquid refrigerant through a connecting chamber 16, which may be of acylindrical form disposed with its axis extending vertically, as shownin Figs. 10, 11, and

. 12. This chamber is disposed at a higher level connects with thechamber 16 above the upper end of the conduit 11 and is preferablyarranged tangentially as shown in Fig. I I. A conduit 19, which isconnected to the chamber 16 below the upper end of the conduit Ti, andwhich is preferably arranged tangentially as shown in Fig. 11, providescommunication with a float valve structure 8!.

In the present embodiment, the refrigerant retaining means isincorporated in the float valve structure 8|, which includes a chamber82 connected to the condenser through the conduit 21, a valve 83 thereinfor controlling the flow of refrigerant to the evaporators through theconduit 19,.and a float member 88 for operating the valve 83. The floatmember 84 comprises upper and lower float elements 840. and 84b, whichare fixed in vertically-spaced relation by a stern 840. A weight member85 is also provided within the chamber 82 and adapted either to rest onthe float member84 or to be lifted by a solenoid coil 86.

I also show, in Fig. 9, one form of control system, which may be appliedto the other embodiments as well as to the one in Fig. 9. This systemcomprises. line conductors L1 and L2, the former being connected to oneterminal of the compressor motor; -A thermostat 81, disposed within thewarmer compartment 68, has one contact connected to the line conductorL2 and the other contact connected to one terminal of the solenoid 88through a conductor 88, while the other terminal of the solenoid isconnected through a conductor 89 to the other terminal of the compressormotor. A thermostat 9| is disposed in the cold compartment 61 andconnected,

between the line conductor L2 and the conductor 89. Each of thethermostats 81 and 9| may 0bviously be of any desired type known in theart and for purposes of illustration are shown as comprising bi-metallicstrips. Each thermostat is adjustable to provide any desired temperaturewithin the respective compartment. In the illustrated embodiment, eachthermostat includes a thumb screw 90, which forms the stationary contactandwhich may be adjusted to vary the temperature setting of thethermostat. It is to be understood that any suitable'form of startingrelay for the compressor-motor may be used, as is fully understood inthe art, and that any other usual electrical provisions may be made.

The operation cf this embodiment is as follows: Assume that the warmercompartment 88 requires refrigeration while the colder compartment 6? issufliciently cold, so that the contacts of the thermostat 8'! are closedwhile the contacts of the thermostat 9| are opened. Thesolenoid 86 andthe compressor motor are both energized, the circuit extending from lineconductor Li through the motor, the conductor 89, the sole-' noid 86,the conductor 88, and the thermostat 81 tothe line conductor-L2. Thesolenoid 86 lifts the weight 85, and the motor drives the compressor 22.The float member 84 being relieved of the weight 85 maintains a lowerliquid level indicated at 92. The refrigerating system is charged with asuflicient quantity of refrigerant, so that, under this condition, thereis suflicient liquid refrigerant conveyed through the conduit 18 to'thechamber 16 to first completely fill the colder evaporator H throughthe conduit 11. and then to supply sufficient refrigerant to the warmerevaporator 15 for operation thereof. The tangential arrangement of theconduit 19 creates a rotating movement of the refrigerant in the chamber16, thereby tending to avoid any intermingling with the liquid in theconduit 11 and the evaporator H. The tangential arrangement of theconduit I8 enables liquid to enter said conduit with minimum disturbanceof the rotating movement in the chamber 16.

The refrigerating systemonow operates in the usual manner of suchapparatus to effect refrigeration of the warmer compartment 68, theliquid refrigerant in the evaporator 15 being vaporized and withdrawnthrough the conduit l9 to the compressor 22, wherein its pressure isincreased. It is then condensed in the con-'- denser and returned to thefloat chamber 82. Due to the higher temperature maintained in thechamber 88, evaporation of liquid refrigerant in the evaporator 15efiects a higher pressure in the low side of the system, which higherpressure isimposed on the liquid ,refrigerant in the evaporator H.However, the increased pressure has no effect on the liquid therein,thereby avoiding condensation and heating of the colder chamber 81 whichwould take place if vapor under the higher pressure were admitted to theevaporator H. Assume now that the temperature in the colder compartment81 rises to the maximum limit for which the thermostat 9| is set so asto close the contacts thereof for effecting refrigeration of saidcompartment. The thermostat 9| 'completes a circuit from line conductorL1 through the motor, the conductor 88, and the thermostat 9| to theconductor L2 to eflfect operation of the motor. The solenoid 86 is nowdeenergized'and releases the weight 85, regardless of whether thethermostat 81 is opened or closed, since, if it is closed, the solenoidis shunted by the thermostat 9|. Accordingly, the weight member 85 restson the float member 84, so that the liquid level within the floatchamber 82 must rise to a higher level, shown at 93, before the floatmember will rise to open the valve 83. There is thus retained in thefloat chamber 82 an additional quantity of liquid refrigerant fillingthe space between the float elements Ma and 8417, which is suflicient toreduce the effective refrigerant charge to the extent that only thecolder evaporator II will receive liquid refrigerant. The liquidrefrigerant remaining in the evaporator 15 from previous operation andthat fllling the vapor space in the top of the header 13 are firstevaporated, as described in connection with Figs. 1 and 2, whilecondensed refrigerant is retained in the float chamber 82 until theupper level 93 is reached. Further operation of the compressor reducesthe suction pressure until evaporation in the evaporator Il takes place.7

The refrigerant system now operates in the usual manner, the refrigerantadmitted to the chamber 18 flowing through the conduit I'I into theheader 13 to supply the colder evaporator 1|, inasmuch as the upper endof the conduit 11 is at a lower level than the inlet end of the conduit18, and there is only sufflcient liquid to cause evaporation in theevaporator I The re erature in the colder compartment 61 is reduced tothe lower limit for which the thermostat 9I is set, thelatter opens itscontacts. If the contacts of the thermostat 81 are open at this time,operation of the refrigeration system ceases but, if they are closed,the solenoid 86 is energized and the motor continues to operate toeffect refrigeration of the warmer compartment in the manner firstdescribed.

In the control system of Fig. 9, the thermostat 9I may be referred to asthe preferred thermostat, since the compartment associated therewithreceives refrigeration in preference to the other when both requirerefrigeration.

In Fig. 13, I show the application of heat exchange apparatus, fortransferring heat from the condensed refrigerant in the high side to thevaporized refrigerant in the low side, applied to the embodiment ofFigs. 9 to 12. One heat exchanger 94 is connected between the evaporatorI5 and the inlet of the compressor, and a second heat exchanger 95 isconnected between the evaporators II and I5. The float chamber 82' isdivided into an upper space 96 containing the float member 84 and alower space 91 containing the valve member 83. The condensed refrigerantis conveyed from the upper chamber 96 through a conduit 98 to the heatexchanger 94, and through a conduit 99 to the heat exchanger 95, andthen through a conduit IOI to the lower chamber SII. From the latter, itis passed through the valve 83 to the conduit 19 and to the evaporatorsin the same manner as in Figs. 9 to 12. It will thus be seen that theliquid collecting in a body in the upper chamber 96 is passed in heatexchange relation with the vaporized refrigerant before its pressure isreduced by the valve member 83.

In Fig. 13, I also 'show a storage chamber I02 connected between thewarmer evaporator 15 and the inlet of the compressor. Should evaporationtake place iri both evaporators at the same time, there may be an excessof liquid returned to the compressor. It is the purpose of the chamberI02 to temporarily retain such liquid to prevent passage thereof to thecompressor and possible damage thereto and loss of refrigeration.Operation of both evaporators might take place under certain conditions;for example, if preference were given to the warmer evaporator insteadof the colder evaporator and the refrigerator had been shut down for aprolonged period allowing both evaporators to acquire a hightemperature, evaporation would take place in both evaporators uponresuming operation of the compressor.

When the evaporator II of Fig. 13 is being refrigerated, the cold densevapor discharged therefrom passes through the heat exchanger 95, inwhich it absorbs heat from the warmer liquid refrigerant being suppliedto the evaporator II, and in which any'liquid particles carried insuspension are vaporized. The cooling gf the liquid refrigerant meansthat a smaller pertion thereof is vaporized as its pressure is reducedbeyond the valve 83, thereby leaving a greater portion of liquidavailable for effecting refrigeration in the evaporator 1I. Thus, therefrigerating effect represented by he capa y of the cold vapor toabsorb sensible heat is returned to'the evaporator 'II to be utilizedtherein. The use of this refrigerating effect in the colder evaporatorII, rather than in the warmer evaporator I5, is advantageous since itreduces the operating time of the colder evaporator, which is at lowerpressure and hence less economical,ratherthanreducing the operating timeof the warmer evaporator, which may be effected more economicallybecause it operates at higherpressure. In other words, the return of therefrigerating effect to the colder evaporator results in a greaterportion of the operation being effected at the higher economy.

The vapor then passes from the heat exchanger 95 to the evaporator I5,but it does not absorb any appreciable amount of heat therein since itstemperature has been raised by the heat exchanger 95. It then passesthrough the heat exchanger in which it extracts further heat from theliquid being supplied to the evaporator II and is further superheated.

, When the evaporator I5 is being refrigerated,

heat exchange takes place in the heat exchanger 95, but has no effect onthe heat balance of the system. The vaporized refrigerant dischargedfrom the evaporator I5, however, absorbs heat from the liquidrefrigerant in the heat exchanger 94 and is superheated in the usualmanner of such heat exchangers.

In Fig. 14, I show another form of control system which effectsenergization of an electrical element, such as a coil, when thenon-preferred thermostat calls for refrigeration. This control mechanismincludes a thermostat T1 which is disposed in the refrigeratorcompartment that is to have preference, and a thermostat T2 disposed inthe other compartment. stat T1 has contacts I02 which are closed andcontacts I03 which are opened when the thermostat calls forrefrigeration and the thermostat T2 is provided with contacts I04 whichare closed when the same calls for refrigeration. The contacts I02 andI04 are connected in parallel in one side of the line going to astarting relay I05. The starting relay is connected to the compressormotor 22 by the necessary number of conductors, including conductors I00connected to the running winding of the motor. A circuit I01 extendsfrom one of the conductors I06 through a coil I09 and the contacts I03to the other conductor, I06. A core I09 is actuated by the coil I08.When the control system of Fig. 14 is applied to the apparatus of Fig.9, the coil 86 and the core 85 constitute the coil I08 and the core I09of Fig. 14, respectively. When it is applied to one of the embodimentshaving a valve for determining which "evaporator shall operate, the coreI09 is connected to the valve in such manner as to effect refrigerationin the preferred evaporator when-the coil I08 is not energized, and toeffect The thermorefrigeration in the non-preferred evaporator partmentI3. The core I09 is connected to the valve 34 was toopen the valve whenthe coil I09 is energized. Assuming that the warmer compartment I3 iscalling for refrigeration and that the colder compartment II is not, thecontacts I03 and I04 are closed and the contacts I02 are opened. Theclosing of the contacts I04 effects energization of the compressor motor22',

and of the conductors I06. The contacts I03 being closed, thecircuit I0!is now closed to energize the coil I08, thereby opening the valve 34 tosupply refrigerant to the warmer evaporator I4. When the thermostat T1in the colder compartment calls for refrigeration, the contacts I02 areclosed and the contacts I03 opened. The contacts I02 effect energizationof the motor and of the conductors I06, but the contacts I03 preventenergization of the'coil I08, regardless of whether the thermostat T .iscalling for refrigeration. The valve 34 is thus closed to causerefrigeration in the colder evaporator I2. When the refrigeration demandof the colder compartment is satisfied, the contacts I03 are closed toenable the thermostat T2 to effect refrigeration .in the warmercompartment. With this control mechanism,

it will be noted that the coil I08 is deenergized to place the apparatusin condition for circulation of refrigerant through the preferredevaporator when neither thermostat is calling for refrigeration. In theapparatus of Figs. 1 and 2, the

valve 34 is closed.

In Fig. 15, I show another form of control mechanism comprisingthermostats T1 and T2 which operate contacts I02 and I04, as in Fig. 14,but in which the thermostat T1 closes contacts I03 when calling forrefrigeration. In this case, the core I09 is arranged or connected toeffect operation of the preferred evaporator when the coil I08 isenergized, and to effect operation of the other evaporator when the coilis deenergized, since the contacts I03 close the circuit I01 when thepreferredthermostat T1 calls for refrigeration".

The operation of this embodiment is as follows: When the thermostat Tlcalls for refrigeration, the contacts I02 effect energization of thecompressor motor 22', and the contacts I03 energize the coil I08 toeffect operation of the preferred evaporator regardless of whether theother evaporator requires refrigeration. When the.

thermostat T2 calls for refrigeration, the contacts I 04 effectenergization of the compressor motor 22, but operation of the evaporatorassociated therewith is effected only when the thermostat T1 becomessatisfied and opens the contacts I03. In this embodiment, the apparatusis conditioned for operation of the non-preferred evaporator whenneither thermostat calls for refrigeration.

The forms of control mechanism shown in Figs. 9 and 14 are suitable forthe apparatus shown in Fig. 9 when the colder compartment is to havepreference, and for the apparatus shown in Fig. 3 when the warmercompartment is to have pref 'erence, since the coil is energized foroperation of the non-preferred evaporator. The control mechanism of Fig.15 is suitable for the apparatus in Fig. 9 when preference is to begiven to the warmer compartment and to the apparatus in Fig. 3 whenpreference is tobe given to the colder relation, as will be readilyapparent from the above description.

In each of the above embodiments, the portions of the low side conduitsoutside the re-.

frigerated compartments are preferably heatinsulated or arranged in somesuitable way to avoid or minimize absorptionof heat. In the embodimentsof the invention shown in Figs. 1,

. 7, 9, and 13, it will be noted that the refrigerantretaining means andthe valve or other means for selecting the evaporator to be operated aredisposed in the high side of the system, so that it is notnecessary toheat insulate the same to prevent condensation of moisture.

therefore, that only su'ch limitations shall be.

placed thereupon as are imposed by the prior art or as are specificallyvset forth in the appended claims.

What I claim is:

1. In refrigerating apparatus, the combination of a low temperature anda higher temperature evaporator, means for condensing the refrigerantvaporized in said evaporators, means for conveying refrigerant from thecondensing means to said evaporators in such man'ner that liquidrefrigerant flows into the low temperature evaporator in preference tothe higher temperature evaporator, and means for selectively producingthe effect of increasing the refrigerant charge to the extent of causingliquid refrigerant to fill a substantial portion of the highertemperature evaporator, for effecting refrigeration at relatively highpressure and temperature in the higher temperature evaporator, orproducing the effect of decreasing the refrigerant charge to the extentthat the higher temperature evaporator receives substantially no liquidrefrigerant, for effecting refrigeration at low pressure and temperature in. the low temperature evaporator.

2. In refrigerating apparatus, the combination of a low temperature anda higher temperature evaporator, means for condensing the refrigerantvaporized in said evaporators, means including a connection to thehigher temperature evaporator and a connect-ion at a lower level to thelow temperature evaporator for conveying refrigerant from the condensingmeans to said evaporators, so that liquid refrigerant flows into the lowtemperature evaporator in preference to the higher temperatureevaporator until a predetermined level is reached and then flows intothe higher temperature evaporator, and means for selectively producingthe effect of increasing'the refrigerant charge to the extent of causingliquid refrigerant -to fill a substantial portion of the highertemperature evaporator, for effecting refrigeration at relatively highpressure and temperature in the higher temperature evaporator, orproducing theefiect of decreasing the refrigerant charge to the extentthat the higher temperature evaporator receives substantially no liquidrefrigerant, for effecting refrigeration at low pressure and temperaturein the low temperature evaporator. I

3. A refrigerating system including two evaporators, one of whichmaintains a lower temperature than the other, said evaporators being soconnected and arranged that liquid refrigerant flows into one evaporatoruntil it is full and then into the other, and means for selectivelydecreasing or increasing the quantity of liquid refrigerant in saidevaporators so that when it is decreased there is liquid beingevaporated in said first evaporator while the other is dry and when itis increased said one evaporator is flooded and under suflicientpressure to prevent vaporization therein while liquid overflows into andvaporizes in said other evaporator to effect cooling therein.

4. A refrigerating system comprising a low temperature and a highertemperature evaporator, means for liquefying refrigerant vaporized insaid evaporators, means for connecting the evaporators and saidliquefying means so that with a predetermined effective charge ofrefrigerant in the system there is sufficient liquid refrigerant in thelow temperature evaporator for effecting refrigeration therein while thehigher temperature evaporator is dry and so that with a second andgreater predetermined effective charge of refrigerant in the systemthere is sufficient liquid refrigerant in the higher temperatureevaporator for effecting refrigeration therein and the low temperatureevaporator is filled with liquid refrigerant to prevent condensationtherein, and means for selectively varying the effective charge ofrefrigerant between said predetermined values.

5. A refrigerating system as specified in claim 4, wherein thelast-mentioned means comprises means for selectively retaining in a partof the system other than the higher temperature evaporator a quantity ofliquid refrigerant equal to the difference between said predeterminedvalues.

6. A refrigerating system having a high side comprising a compressor anda condenser and a low side comprising a low temperature evaporator and ahigher temperature evaporator, means for supplying condensed refrigerantfrom the condenser to the evaporators, the low temperature evaporatorbeing connected to the refrigerant supply means at a lower level thanthe higher temperature evaporator so that the former has preference inreceiving liquid refrigerant and the latter receives liquid refrigerantonly when the low temperature evaporator has its full amount of liquidrefrigerant, and means for selectively varying the effective charge ofrefrigerant in the system so that, in one condition, only the lowtemperature evaporator receives liquid refrigerant and, in a secondcondition, both the low temperature and the high temperature evaporatorreceive liquid refrigerant.

7'. A refrigerating system comprising a low temperature and a highertemperature evaporator, means for condensing the refrigerant vaporizedin said evaporators, said evaporators and the condensing means being soconnected that the low temperature evaporator receives liquidrefrigerant in preference to the higher temperature evaporator until itis substantially filled, the system containing a suflicient charge ofrefrigerant to substantially fill the low temperature evaporator withliquid refrigerant and to supply sufficient liquid refrigerant to thehigher temper-- ature evaporator to provide refrigeration therein, andmeans for selectively retaining in a portion of the system other thanthe high temperature evaporator a sufficient quantity of liquidrefrigerant to cause the higher temperature evaporator to become drywhile retaining sufficient liquid refrigerant in the low temperatureevaporator to efiect refrigeration therein or releasing the same toeffect refrigeration in the higher temperature evaporator.

8. The method of operating a refrigerating system having a lowtemperature and a higher temperature evaporator which comprisessupplying liquid refrigerant to the low temperature evaporator andmaintaining the higher temperature evaporator dry for effectingrefrigeration in the low temperature evaporator, and supplying liquidrefrigerant to the higher temperature evaporator and efiectingevaporation of liquid refrigerant therein at a temperature above thetemperature of the low temperature evaporator and at a pressure higherthan the pressure corresponding to said temperature of the lowtemperature evaporator, and at the same time supplying liquidrefrigerant to the low temperature evaporator to fill the same forpreventing condensation of vaporous refrigerant therein.

9. A refrigerating system comprising a low temperature evaporator and ahigher temperature evaporator, said evaporators being so connected thatliquid refrigerant flows into the low temperature evaporator inpreference to the high temperature evaporator until the former issubstantially filled and then flows into the latter,

means for removing the refrigerant vaporized in said evaporators andcondensing the same, a high side float valve for controlling flow ofrefrigerant from said condensing means to said evaporators,

said float valve including a chamber and a float member therein, andmeans for selectively imposing additional downwarclbias on said floatmember to raise the liquid level within the chamber to a point where theadditional liquid refrigerant retained in the float chamber prevents thehigher temperature evaporator from receiving liquid refrigerant.

10. In refrigerating apparatus, the combina-'. tion of a low temperatureand a higher temperature evaporator, means for condensing therefrigerant vaporized in said evaporators, and means for selectivelysupplying liquid refrigerant to the low temperature evaporator andmaintor until the same is substantially filled with liquid refrigerant.

11. Refrigerating apparatus as defined in claim 10, wherein the liquidrefrigerant in the low temperature evaporator remains in substantiallystatic condition while refrigeration is effected in the highertemperature evaporator.

12. In refrigerating apparatus, the combination of lower temperature andhigher temperature evaporators in free communication with each other sothat the pressure therein is the same, means for withdrawing vaporizedrefrigerant from said evaporators and for condensing the same, and meansfor selectively supplying liquid refrigerant to the higher temperatureevaporator and effecting evaporation of liquid refrigerant therein at atemperature above the temperature of the lower temperature evaporatorand at a pressure higher than the pressure corresponding to saidtemperature of the lower temperature evaporator and atthe same timesupplying liquid refrigerant to the lower tempera- 5 peration of colderevaporator and ata pressure higher than the pressure corresponding tosaid temperature of the colder evaporator'and at the same timepreventing condensation of vaporous refrigerant in the colderevaporator, and means for supplying liquid refrigerant to the colderevaporator for operation thereof-at lower pressure and at the. same timemaintaining the warmer evaporator substantially dry.

14. In refrigerating apparatus, the combination of a colder and a warmerevaporator operating at different times, means for withdrawing vaporizedrefrigerant from said evaporators and for condensing the same, means forsupplying liquid to the colder evaporator for operation thereof at lowerpressure while preventing evaporation of liquid refrigerant in thewarmer evaporator.

15. In refrigerating apparatus, the combination of a low temperature anda higher temperature cooling element, and means for selectivelycirculating cooling medium first through the low tema perature coolingelement for extracting heat therein and then through the highertemperature cooling element or circulating cooling medium through thehigher temperature cooling element for extracting heat thereinwithoutextracting '0 any appreciable amount of heat in the lowtemperature cooling element.

16. A frigerating comprising, in combination, a a

cf evaporators, and means for selectively effecting either evaporator,said last-menmeans comprising means for selectively reclosing theelective refrigerant charge inthe 17. In refrigerating apparatus,thecombination Q of a comprmr, a condenser. a plurality of evapcraters, acommon device for said evaporators, and means forselectively eflectingoperation of either evaporator comprising a chamher and means forselectively retaining a quantity of liquid refrigerantin'saidchamben-theretenflonotapredeterminedquantityofliquidrefrigin at atemperature above the temperature of the refrigerant to the warmerevaporator and effectcondenser, a plurality 18. In. refrigeratingapparatus, the combination of a colder and a warmer evaporator, acompressor for withdrawing vaporized refrigerant from the evaporators, acondenser, a device for controlling flow of condensed refrigerant to theevaporators, means for conveying refrigerant from said device to saidevaporators, said conveying means and said evaporators being connectedand arranged so that the evaporators are in communication and atsubstantially the same pressure at all times, so that liquid refrigerantflows into the colder evaporator in preference to the warmer evaporatorand into the warmer evaporator only after the colder evaporator issubstantially filled with liquid refrigerant, so that the liquidrefrigerant in the colder evaporator may remain in a substantiallystatic condition when the colder evaporator is filled and liquidrefrigerant is supplied to the warmer evaporator, so that refrigerantmay flow through the warmer evaporator at all times, and so thatoperation of -the warmer evaporatordepends on whether there issufficient liquid refrigerant to spill over into the warmer evaporator,and means for selectively increasing the flow of liquid refrigerant toan extent causing the same to spill over into the warmer evaporator orreducing the flow thereof to an extentpreventing such spilling over andthereby depriving the warmer evaporator of liquid refriger t.

In refrigerating apparatus, the combination of a colder and a warmerevaporator element, and means for selectively circulating refrigerantfirst through the colder evaporator element and extracting heat thereinby evaporation of liquid reirigerant at low pressure and then throughthe warmer evaporator element or circulating refrigerant through thewarmer evaporator element and effecting evaporation of liquidrefrigerant therein at a temperature above the temperature of the colderevaporator element and at a pressure higher than the pressurecorresponding to said temperature of the colder evaporator elementwithout adding an appreciable amount of heat to the colder evaporatorelement.

.20. In a refrigerating system, the combination of a colder evaporatorand a warmer evaporator, means including a compressor and a condenserfor effecting evaporation of liquid refrigerant in said evaporators andfor supplying liquid refrigerant thereto, means for selectivelyeifecting evaporation of liquid refrigerant in the colder evaporator bysupplying liquid refrigerant to the colder evaporator only or in" thewarmer evaporator' by supplying liquid refrigerant to both evaporators,and a connection providing communication between said evaporators at alltimes, said connection being arranged so that liquid refrigerant flowsfrom said connection to the colder evaporator in preference to thewarmer evaporator and therebyserves to prevent flow of liquidrefrigerant to the warmer evaporator when said second-mentioned means isadjusted for effecting evaporation of liquid refrigerant in the colder

